Armoured personnel carrier
An armoured personnel carrier (APC) is type of armoured fighting vehicle designed to transport infantry to the battlefield. APCs are colloquially referred to as 'battle taxis' or 'battle buses', among other things.
APCs differs from other AFVs, namely infantry fighting vehicles, due to the weaponry they carry. The Treaty on Conventional Armed Forces in Europe defines Armoured personnel carriers as "an armoured combat vehicle which is designed and equipped to transport a combat infantry squad and which, as a rule, is armed with an integral or organic weapon of less than 20 millimeters calibre."
By convention they are not intended to take part in a direct-fire battle, but to provide additional protection from shrapnel and small arms fire. Examples include the American M113, the French VAB, the Dutch/German GTK Boxer and the Soviet BTR.
The genesis of the armoured personnel carrier concept was on the Western Front of World War I. In the in the later stage of the war, Allied tanks could break through enemy lines, however the infantry following who were needed to consolidate the gains still faced small arms and artillery fire. Without infantry support, the tanks were isolated and subsequently destroyed. In response, the British introduced the Mark V*, which was a version lengthened to include a troop compartment, and the purpose built Mark IX tank. Though a revolution in armoured doctrine, they had little impact on the war.
During World War II, half-tracks, notably the M3 and the SdKfz 251 played a role similar to post-war APCs. Over the course of the war APCs evolved from simple armoured cars, with transport capacity, to purpose built vehicles.
Obsolete armoured vehicles have often been repurposed as APCs. The inception of this concept was in 1944, with the introduction of the Kangaroo-type carrier. The initial conversion of 72 M7 Priest self-propelled howitzers was followed by the conversion of Churchill, M3 Stuart, and most heavily Ram, tanks. A later example of this concept is the Israeli Achzarit.
During the Cold War, different specialised APCs were developed. The United States developed a series of tracked vehicles, including successors to the wartime Landing Vehicle Tracked, but the most prolific of these was the M113, of which 80,000 were produced. Western nations have largely phased out the M113 and replaced it with newer models, mostly wheeled vehicles. The Soviet Union produced the BTR-40, BTR-152, BTR-60, BTR-70, BTR-80 and BTR-90 in large numbers. The BTR-60, 80, and 90 remain in production in the East.
APCs can vary in weight of 6 tons to 40 tons or more; though a typical vehicle will be between 9 and 20 tons. They typically have a capacity of between 8 and 12 dismountable troops, though some models can carry more than a score. By definition, an APC will have capacity for a combat infantry squad. 
An APC will have at least one crewman, the driver, with as many as three, a gunner and commander.
An APC is either wheeled or tracked, or occasionally a combination of the two, as in a half-track. Both systems have their own advantages and limitations. Tracked vehicles have more traction offroad and more maneuverability, including a minute turn radius. Wheeled APCs are faster on road, and can cross long distances; typically, due to the limited lifetime of the treads, and the wear they cause on roads,  tracked vehicles are transported cross country by rail, or a flatbed truck which may or may not be a purpose built transporter.
Wheeled vehicles have higher ground pressure than tracked vehicles with a comparable weight, due to tracks having more surface area in contact with the ground. The higher ground pressure increases the likelihood of becoming immobilized by terrains such as mud, snow, or sand.
Many APCs are amphibious. Tracked APCs are powered by their tracks, and wheeled APCs will include propellers or water jets. Preparations for amphibious operations usually comprises checking the integrity of the hull and folding down a trim vane in front. Water traverse speed varies greatly between vehicles. The max swim speed of the M113 is 3.8 mph, whereas the LAV-25 and AAVP-7 can reach nearly double that at a maximum of 6.5 and 8.2 mph, respectively.
APCs must provide a minimum amount of protection against small arms fire to be considered as such, though some provide as much protection as a main battle tank, as is the case of the IDF Namer, which is based on a Merkava tank. Armour is usually composed of steel or aluminium. Some APCs also come with NBC protection, which is intended to provide protection from weapons of mass destruction.
Generally APCs will be lighter and less armoured than tanks or IFVs, often being open topped and featuring doors and windows, as seen in the French VAB.
An APC carries a primary weapon of at most a 20mm autocannon before falling into the infantry fighting vehicle sub-classification, and will most likely be outfitted with one or more machine guns ranging from 5.56mm to 7.62mm. The primary weapon will usually be mounted on the top of the vehicle, either a simple pintle mount, in a small turret, or on a remote weapon system.
Pintle mounted weapons are rare, due to the lack of crew protection. The World War II Axis half-track Sd.Kfz. 251 was equipped with at least one MG42 or MG34, which could only be aimed in a small arc from whichever end of the vehicle the weapon was mounted and offered minimal protection to the gunner. Turrets, by definition, provides a traversal range of 360 degrees and operator protection. Most APC turrets include a coaxial machine gun(MG) alongside the primary weapon; for example the BTR, BMP, and LAV series carry MGs alongside primary weapons, however the basic MTLB's turret carries only a 7.62mm MG. A recent advent, remote weapon systems are used in lieu of pintle mounts and provide the same level of operator protection as a turret, with the added benefit of increased visibility without increasing the overall profile of the vehicle. However, unlike in a turret, the weapon cannot be reloaded from inside the vehicle.
A common primary gun on an APC is an M2 Browning 50 caliber machine gun, or the equivalent 14.5mm KPV heavy machine gun. The Stryker carries an M2 on a CROWS, and many IMVs mount one on a RWS or pintle mount. 7.62mm machine guns like the FN MAG (L8, C6, M240), PKT machine gun, and equivalent are commonly used models as coaxial or secondary weapons. Several Eastern personnel carriers have forward facing machine guns, or firing ports, in the crew compartment. The AAVP7 mounts an M2 50 caliber as a coaxial machine gun beside a Mark 19 automatic grenade launcher. Occasionally APCs will be equipped with anti-tank guided missiles.
Armoured personnel carriers may be used as ambulances to conduct medical evacuations of wounded personnel, acting in the same capacity as an ambulance but granting more protection to passengers. These vehicles are equipped with stretchers and medical supplies. According to article 19 of the Geneva Conventions, mobile medical units of the Medical Service may in no circumstances be attacked, but at all times be respected and protected by the Parties to the conflict, and under article 22 are allowed to carry defensive weaponry though are typically unarmed.
Under Article 39 of the convention [the emblem of the medical service] shall be displayed ... on all equipment employed in the Medical Service. As such, armoured ambulances will be marked with ICRC symbols, such as the Geneva cross or Red Crystal.
Infantry Fighting vehicle
The infantry fighting vehicle is a derivative of the APC. Various classes of infantry fighting vehicles are deployed alongside tanks and APCs, in armoured and mechanized forces respectively. The fundamental difference between with an IFV beyond the definition outlined in the CFE treaty is the role they were designed to serve. The CFE stipulates an infantry fighting vehicle is an APC with a cannon in excess of 20mm, and with this additional firepower the vehicle acts in a more involved combat role, providing fire support to dismounted infantry. The LAV-III, the primary mechanized infantry vehicle of the Canadian armed forces, is classified as an IFV due solely to its M242 Bushmaster autocannon. The M2 Bradley carries the same weapon and classification, but is heavily armoured, outfitted with TOWs and advanced optics, and serves primarily in US Army armoured divisions alongside M1 Abrams Main battle tanks.
The BTR-90, which mounts a 30mm autocannon and anti-tank missile, is colloquially referred to as an APC. BTR, literally translated, means "armoured transporter." However the BMP-3, literally "Infantry Combat Vehicle", is equipped with a slew of heavy weaponry including a 100mm gun, and not generalized in the same manner.
Infantry Mobility Vehicle
Infantry Mobility vehicle is a neologism to describe a decades old concept of an armoured car with increased mine resistance and passenger protection for use primarily in unconventional theatres of war. Though beginning as early as the 1970s with vehicles such as the South African Casspir, they only came into favour in the 21st century in the post-Soviet geopolitical climate.
The American uparmoured Humvee, classified as M1114, is the epitome of the IMV concept. The M1114 is identical to the Humvee, in both design and function, apart from the addition of several tons of armour. The M1114 was later replaced in the role by the purpose built vehicles of the MRAP program, a series of vehicles inspired by the Casspir.
IMVs generally feature a v-hull shaped underbelly with additional crew protection features such as four- point seat belts and seats suspended from the roof or sides of the vehicle. Many feature a remote weapon system in place of a crew-served weapon system.
|Wikimedia Commons has media related to Armoured personnel carrier.|
- Treaty on conventional armed forces in Europe. Organization for Security and Co-operation in Europe. 1989. p. 3. Retrieved 4 April 2013.
- Skaarup, Harold A. "Ironsides: Canadian Armoured Fighting Vehicle Museums and Monuments." Google Books. N.p., 2011. Web. 04 Apr. 2014. page 140
- Bishop, Chris (2006). The Encyclopedia of Tanks and Armored fighting vehicles: From World War I to The Present Day. Grange Book. ISBN 978-1-59223-626-8
- O'Malley, T. J., Hutchins, Ray (1996). Fighting Vehicles: Armoured Personnel Carriers & Infantry Fighting Vehicles. Greenhill Books. ISBN 1-85367-211-4